PCM

The abreviation of Pentocyleinicmethylhydrane, used by the Usurians to pacify their slave populations to minimise the need for huge numbers of guards, it apparently eliminates air-bourne infection (the Doctor seems to confirm that it does that), although it has a side-effect that affects the nervous system by inducing anxiety, thus debilitating the will of those affected, it is less effective in the Undercity of Megropolis 1 and in the mines of Megropolis 3 (where the miners live).

There is an antidote to this anxiety inducing agent made in the chemical plant, which only higher executive grades are allowed to take (marked "for official use only").